Facile Approach to Enhance Activity and CO₂ Resistance of a Novel Cobalt-Free Perovskite Cathode for Solid Oxide Fuel Cells

Abstract

Developing high-performance and cost-effective cathodes is ever-increasingly vital for the advancement of intermediate-temperature solid oxide fuel cells (IT-SOFCs). To facilitate the popularization of nonprecious metallic and cobalt-free oxygen reduction electrodes, herein, we propose a novel perovskite-based BaFeO3−δ (BF) matrix, Ba0.75Sr0.25Fe0.875Y0.125O3−δ (BSFY), as a highly active cathode for IT-SOFCs. To our satisfaction, the BSFY electrode showcases a low area-specific resistance of 0.063 Ω cm2, as well as a high peak power density of 1288 mW cm–2 at 600 °C, yielding a more than threefold improvement compared to that of its BF counterpart (371 mW cm–2). The long-term durability test highlights its practicability under the IT operating condition. When tested in 10 vol % CO2-containing air, the BSFY electrode exhibits impressive resistance against contaminants within 50 h (<0.4 Ω cm2 with a deterioration rate of ∼0.00011 Ω cm2 min–1). Coupled with its reversible response between pure air and the contaminant, the BSFY cathode is expected to be a promising cobalt-free alternative with high CO2 resistance for IT-SOFCs.

CO2-tolerant perovskite cathodes for enhanced solid oxide fuel cells: advancements, challenges, and strategic perspectives

“…, all of which have demonstrated increased resistance to CO 2 poisoning. 62,85–91 The above investigations underscore the promising potential of multi-cation synergy in developing highly CO 2 -resistant cathode candidates.…”

“…This approach enables the BSFY electrode to showcase impressive CO 2 -tolerance with an ultralow deterioration rate of ∼0.00011 Ω cm 2 min −1 , surpassing that of a great majority of reported CO 2 -resistant perovskite analogues. 86 Seeking further enhancement, we formulated a composite cathode with a nominal composition of Bi 0.7 Pr 0.1 Ba 0.2 FeO 3− δ (BPBF) and SDC for short-term contaminant poisoning tests. Encouragingly, the BPBF-based electrode performs stably with a constant electroactivity of 0.31 Ω cm 2 at 600 °C over a 50 h period, suggesting its significant potential as a practical air electrode material.…”

“…To date, various heteroatomic metallic dopants with high acidity, such as Sb, Bi, Ti, Ga, etc., have been explored to enhance the CO 2 -resistance of perovskite materials. [81][82][83][84][85][86] Taking the Sb dopant as an illustrative example, owing to the augmented acidity of Sb 5+ compared to Fe 3+/2+ , Sb-incorporating Bi 0.5 Sr 0.5 FeO 3−d (Bi 0.5 Sr 0.5 Fe 0.9 Sb 0.1 O 3−d ) demonstrated a substantially reduced degradation rate relative to its undoped counterpart under identical CO 2 concentrations. 81 Xia et al further proposed that the Sb-doped behavior is favorable for structural robustness and CO 2 adsorption/desorption capacity, hence resulting in superior CO 2 -tolerance, as corroborated by the combined experimental and computational analyses.…”

Facile Deficiency Engineering in a Cobalt‐Free Perovskite Air Electrode to Achieve Enhanced Performance for Protonic Ceramic Fuel Cells

“…A wide range of cathode modification methods have been proposed to promote electrochemical performance, including element doping, defect regulation, surface decoration, and composite engineering. [17][18][19][20] Studies have revealed that the catalytic properties of perovskite oxides for ORR are closely associated with oxygen vacancies, which have a significant impact on the crystal structure, electronic properties, as well as surface chemistry of the materials. [21] The defect regulation at the A-or Bsite is valued as the most direct and feasible strategy to tune the oxygen vacancies in typical perovskite oxides.…”

A Highly Efficient and Robust Bifunctional Perovskite‐Type Air Electrode with Triple‐Conducting Behavior for Low‐Temperature Solid Oxide Fuel Cells

“…[5][6][7] In retrospect, numerous perovskite-type oxides with mixed ionic-electronic conducting nature have been employed for oxygen-ion conducting SOFCs (O-SOFCs), as well as proton conducting SOFCs (H-SOFCs). [8][9][10][11][12] Unlike the traditional pure electronic conductor where the reaction active sites only locate at the threephase boundary, mixed ionic-electronic conducting perovskites can extend the active area to entire phase surface, thereby achieving desirable oxygen reduction reaction (ORR) activity. [13,14] Some highly promising electrode materials have been reported with exclusivity for O-SOFCs or H-SOFCs, however, up to now, there is a lack of highly efficient bifunctional electrodes for both SOFCs owing to the difference in cathode reaction mechanisms.…”